Low temperature thin wafer backside vacuum process with backgrinding tape

ABSTRACT

Vacuum processing, such as a backside metallization (BSM) deposition, is performed on a taped wafer after a gas escape path is formed between a base film of the tape and the wafer frontside surface following backgrind. Venting provided by the gas escape path reduces formation of bubbles under the tape. The gas escape path may be provided, for example, by a selective pre-curing of tape adhesive, to breach an edge seal and place the wafer frontside surface internal to the edge seal in fluid communication with an environment external to the edge seal. With the thinned wafer supported by the pre-cured tape, BSM is then deposited while the wafer and tape are cooled, for example, via a cooled electrostatic chuck.

TECHNICAL FIELD

Embodiments of the present invention generally relate to microelectronicfabrication and more particularly to backside vacuum processing of thinsubstrates.

BACKGROUND

Microelectronics fabrication is conventionally performed on a bulksubstrate, often referred to as a wafer. Bulk substrate thicknesses aretypically 700-800 μm (microns) for the most common silicon wafer.Advanced packaging applications, such as thin die, thin thermalinterface material (TDTT), 3DIC (i.e., chip stacking), etc. utilizesubstrates thinned to below 400 μm. After wafer thinning, vacuumprocessing may be performed. For example, copper and/or other metals maybe deposited onto the wafer backside during a backside metallization(BSM) process to form thermal contacts, or to form copper bumps, underbump metallization (UBM), etc., electrically connecting to themicroelectronic devices. Depending on the metals and thickness of theBSM, the BSM deposition process (e.g., sputtering) often elevates thewafer temperature (e.g., to 150° C.-300° C., or more).

One of the many manufacturing issues with such thin substrates is how toperform vacuum processing such as the BSM deposition. Many rigid carriersolutions, referred to collectively as wafer support systems (WSS), havebeen proposed where, for example a rigid glass disc, or silicon carrierwafer is attached to the thinned wafer. While some of these solutionsare compatible with the elevated processing temperatures, they allsuffer from complexity and attendant high cost.

Another proposed solution is to employ the backside grind (BG) tape thatis applied to the wafer frontside during a back grind (BG) process as ameans of support and handling during the vacuum processing. However,such tape is typically lacks stiffness sufficient for support, and tokeep the BG tape adhesive from thermally decomposing at elevatedprocessing temperatures, such as those during BSM deposition, substratecooling is applied during the vacuum process. While this may in theorybe accomplished via an electrostatic chuck (ESC) to hold the BG tape andthin wafer onto a cooled chuck in a vacuum system, because suchelectrostatic force is a function of distance between the thin wafer andthe chuck, it is difficult in practice to keep the frontside of thewafer uniformly close to the chuck. Because air is often unavoidably, ordeliberately, entrapped between the BG tape and frontside topologies(frontside bumps, etc.), air bubbles form between the BG tape and thefrontside of the wafer, become large under vacuum, and increase thermalresistance between the cooled chuck and wafer. Such air bubbles can leadto significant thermal gradients and localized wafer bowing, either ofwhich can ultimately cause breakage of the wafer during the vacuumprocess and a complete loss of hundreds, if not thousands, of fullyfabricated microelectronic devices.

A low temperature thin wafer vacuum process overcoming these issues istherefore advantageous for BSM deposition and other similarly demandingvacuum processes.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not limitation, in the figures of the accompanying drawings inwhich:

FIG. 1 is a flow diagram illustrating a backside vacuum processingmethod, in accordance with an embodiment of the present invention;

FIG. 2 is a flow diagram illustrating a BSM method, in accordance withan embodiment of the present invention;

FIGS. 3A, 3B, and 3C illustrate cross-sectional and plan views of ataped wafer as it is processed through certain operations of the methodof FIG. 1 or FIG. 2, in accordance with an embodiment;

FIGS. 4A, 4B, 4C, 4D, 4E, and 4F illustrate cross-sectional and planviews of a taped wafer as it is processed through certain operations ofthe method of FIG. 1 or FIG. 2, in accordance with an embodiment;

FIGS. 5A, 5B, 5C, 5D, 5E, and 5F illustrate cross-sectional and planviews of a taped wafer as it is processed through certain operations ofthe method of FIG. 1 or FIG. 2, in accordance with an embodiment;

FIGS. 6A and 6B illustrate plan and side view schematics of a UV cureapparatus to perform a pre-cure operation of the BSM method in FIG. 2,in accordance with an embodiment;

FIGS. 7A and 7B illustrate plan and side view schematics of a UV cureapparatus to perform a pre-cure operation of the BSM method in FIG. 2,in accordance with an embodiment;

FIG. 8 is a flow diagram illustrating a frontside tape pre-cure method,in accordance with an embodiment of the present invention; and

FIG. 9 is a block diagram of a computer system configured to perform thefrontside tape pre-cure method illustrated in FIG. 8, in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth, however,it will be apparent to one skilled in the art, that embodiments of thepresent invention may be practiced without these specific details. Insome instances, well-known methods and devices are shown in blockdiagram form, rather than in detail, to avoid obscuring embodiments ofthe present invention. Reference throughout this specification to “anembodiment” means that a particular feature, structure, function, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in an embodiment” in various places throughout thisspecification are not necessarily referring to the same embodiment ofthe invention. Furthermore, the particular features, structures,functions, or characteristics may be combined in any suitable manner inone or more embodiments. For example, a first embodiment may be combinedwith a second embodiment anywhere the two embodiments are not mutuallyexclusive.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe structural relationships between components.It should be understood that these terms are not intended as synonymsfor each other. Rather, in particular embodiments, “connected” may beused to indicate that two or more elements are in direct physical orelectrical contact with each other. “Coupled” my be used to indicatedthat two or more elements are in either direct or indirect (with otherintervening elements between them) physical or electrical contact witheach other, and/or that the two or more elements co-operate or interactwith each other (e.g., as in a cause an effect relationship).

The terms “over,” “under,” “between,” and “on” as used herein refer to arelative position of one material layer with respect to other layers. Assuch, for example, one layer disposed over or under another layer may bedirectly in contact with the other layer or may have one or moreintervening layers. Moreover, one layer disposed between two layers maybe directly in contact with the two layers or may have one or moreintervening layers. In contrast, a first layer “on” a second layer is indirect contact with that second layer.

FIG. 1 is a flow diagram illustrating a backside vacuum processingmethod 100, in accordance with an embodiment of the present invention.The method 100 begins at operation 101 with a thinned wafer having tapelaminated to a frontside of a wafer. FIG. 2 is a flow diagram furtherillustrating a BSM method 200 in accordance with an embodiment of thepresent invention that is inclusive of tape application at operation 201and backgrinding of the wafer at operation 205 to arrive at a materialsuitable for using in operation 101 of method 100.

FIGS. 3A, 3B, and 3C illustrate cross-sectional and plan views of ataped wafer 300 as it is processed through certain operations of theprocesses of FIG. 1 or FIG. 2, in accordance with an embodiment.Referring to FIG. 3A, the thin wafer 301 has frontside topography 305,for example metallization such as copper bumps, pads, etc., which mayfor example extend 10-40 μm, or more, from a nominal frontside surfacewhere each of a plurality of microelectronic devices (not illustrated)are fabricated on the thin wafer 301. Generally, the microelectronicdevices may be any integrated circuit and embodiments of the presentinvention are not limited in this respect. Exemplary microelectronicdevices include memory, such as, but not limited to, dynamic randomaccess memory (DRAM,) non-volatile random access memory (NVRAM), NOR andNAND flash memory, etc., microprocessors, application specificintegrated circuits (ASICs), floating point gate arrays (FPGA), etc.,optical devices, such as light emitting diodes (LEDs), active pixelsensors (APS), and Microelectromechanical systems (MEMS). While thethinned wafer 301 may generally be of any material suitable forsemiconductor device fabrication, in advantageous embodiments it iscomposed of a single crystalline material such as, but is not limitedto, silicon, germanium, silicon-germanium, or a III-V compoundsemiconductor material. The thin wafer 301 may also be a semiconductor(silicon) on insulator (SOI) substrate having a buried insulator layer(e.g., silicon dioxide) spanning the entire area of the thin wafer 301,as known in the art.

In an embodiment, the thin wafer 301 (e.g., following operation 205) isto have a thickness below 400 μm but sufficiently thick that a rigidsupport (e.g., WSS) is not structurally required for vacuum processing(e.g., BSM deposition). In other words, the thin wafer 301 is ofsufficient thickness that when combined with a semi-rigid support,somewhat more rigid that conventional BG tape, BSM processing ispossible with commercially available robotic handling and wafer clampingmeans. In exemplary embodiments, the thin wafer 301 is between 150 μmand 400 μm thick and advantageously between 150 μm and 250 μm thick.

Laminated to a frontside of the thin wafer 301 is a frontside tape 306,such as the backgrind (BG) tape attached at operation 201 in FIG. 2 tofacilitate the backgrind operation 205. The frontside tape 306 includesa base film 320 and an adhesive 310. In the exemplary embodiment, thebase film 320 has sufficient stiffness to serve as the semi-rigidsupport of the thin wafer 301. In other words, no rigid support ring orother mechanical means is further provided in addition to the frontsidetape 306 to support the thin wafer 301 during vacuum processing (e.g.,BSM deposition). As stiffness is an extensive material property, eitherthickness or composition of the base film 320 may be selected to achievethe stiffness needed for a particular combination of wafer thickness andvacuum processing equipment.

As one exemplary embodiment, the base film 320 is ethylene vinyl acetate(EVA). For such an embodiment, semi-rigidity may be provided byincreasing the thickness of the EVA base film 320 beyond that ofconventional BG tape, for example to at least 300 μm for thoseembodiments where the thin wafer 301 has a thickness of around 200 μm.Thicknesses much beyond about 400 μm should not be necessary for an EVAbase film 320 unless the thin wafer 301 has a thickness significantlybelow 200 μm (e.g., 150 μm). For embodiments employing a stiffer basematerial, base film thickness may be corresponding less. In anotherembodiment for example, the base film 320 is polyethylene (PET) of atleast 100 μm thick where the thin wafer 301 has a thickness of around200 μm. Notably, while thinner than the exemplary EVA embodiments, thePET embodiments are still two to three times the thickness ofconventional BG tape having a PET base film. Thicknesses much beyondabout 200 μm should not be necessary for a PET base film 320 unless thethin wafer 301 has a thickness significantly below 200 μm (e.g., 150μm).

Depending on the class of frontside tape, the adhesive 310 may beuniformly dispersed over the entire surface area of the tape, asillustrated in FIG. 3A. In alternative embodiments, frontside tapeadhesive is non-uniformly dispersed, as illustrated by adhesive 410 inFIG. 4A and adhesive 510 in 5A. For all classes of frontside tapehowever, the adhesive forms an edge seal to protect the previouslyfabricated frontside structures (e.g., topographic features 305 andassociated microelectronic devices) from external contaminants, such asbackgrind slurry and debris generated during wafer thinning. Inembodiments, the adhesive 310 is a UV-curable composition.

Referring first to FIG. 3A, for a first class of tape the adhesive 310fully encapsulates the topographic features 305 such that the adhesive310 contacts the thin wafer 301 even at a base 303 between two adjacenttopographic features 305. As shown in cross-section in FIG. 3A, and asalso shown in plan view by FIG. 3B, the adhesive 310 forms a continuousedge seal 322 at the wafer edge surrounding a frontside interior surfaceregion 325 of the wafer (i.e., internal to the edge seal 322). Shown inFIG. 4A is a second class of taped wafer 400 where the adhesive 410 onlypartially encapsulates the topographic features 305 such that theadhesive 410 is not present at the base 303 between two adjacenttopographic features 305. Nevertheless, as shown in cross-section inFIG. 4A, and as also shown in plan view by FIG. 4B, the adhesive 410forms a continuous edge seal 420 at the wafer edge surrounding afrontside interior surface region 425 of the wafer (i.e., internal tothe edge seal 420). Shown in FIG. 5A is a third class of taped wafer500, often referred to as no-residue-tape (NRT), where the adhesive 510encapsulates no portion of the topographic features 305. Again however,as shown in cross-section in FIG. 5A, and as also shown in plan view byFIG. 5B, the adhesive 510 is present to the extent necessary to form acontinuous edge seal 520 at the wafer edge (i.e., at a perimeter of thebase film 320) surrounding a frontside interior surface region 525 ofthe wafer (i.e., internal to the edge seal 522).

Returning to FIG. 1, at operation 110, a gas escape path is formed tobreach the edge seal formed by the adhesive on the frontside tape. FIG.3C illustrates a gas escape path 350 along the a-a′ cross-section linethat is formed into a fully encapsulating tape embodiment. As shown,along the gas escape path 350, the adhesive 310 between the base film320 and the frontside surface of the thin wafer 301 is separated. Thegas escape path 350 however places the wafer frontside interior surfaceregion 325 internal to the edge seal 322 in fluid communication withenvironments external to the edge seal 322 while retaining theprotective physical barrier over the frontside microelectronic deviceand topographic features 305 and while retaining support of the thinnedwafer provided by the semi-rigid base film 320. As the gas escape path350 is formed after wafer thinning, there is little concern forfrontside contamination. With the gas escape path 350 formed, the tapedthin wafer has sufficient rigidity to be processed under vacuumconditions with fabrication equipment conventionally utilized for fullthickness wafers or rigidly supported wafers without significantbubbling of the frontside tape.

In an embodiment, and as further illustrated in FIG. 2, a gas escapepath may be formed by pre-curing the tape at operation 210 over at leasta portion of the frontside surface area of a thin wafer to separate theadhesive from only a portion the wafer frontside. The pre-curing mayentail any conventional curing technique typically utilized for detapebased on the particular adhesive chosen. In certain embodiments,exposure dose and time is sufficient for complete, full curing of theadhesive (i.e., no further desirable change with additional cure time).

Referring to FIG. 3A where the frontside topography 305 is fullyencapsulated by the adhesive 310, the entire frontside surface area maybe exposed to UV radiation (i.e., irradiated) to separate the adhesive310 from the wafer frontside at the edge seal 322 while maintainingadhesive contact with the topographic features 305, as further shown inFIG. 3C. It has been found that although shrinkage of the adhesive 310upon UV cure will open the edge seal and also a network of gas escapepaths throughout the frontside surface (e.g., at the base 303 betweentwo adjacent topographic features 305) that extend into the waferfrontside interior surface region 325, sufficient contact is maintainedwith the frontside topography 305 for the frontside tape to serve as thesemi-rigid support during subsequent vacuum processing (e.g., BSMdeposition).

Referring to FIGS. 4C and 5C, where the frontside topographic features305 are either only partially encapsulated or unencapsulated,respectively, pre-curing of the frontside tape at operation 210 entailsselectively forming escape paths between retained portions of anadhesive edge seal. For example as shown in FIG. 4C, edge seal portions420-1, 420-2, 420-3 and 420-4 are separated by intervening escape paths450. As illustrated in FIGS. 4E and 4F, between the gas escape paths450, the edge seal portions 420-1, 420-2, 420-3 and 420-4 remain adheredto the thin wafer 301 and provide support to the thinned wafer. Asfurther illustrated in FIGS. 5E and 5F, for NRT embodiments, after thepre-cure operation 210, support of the thin wafer 301 is limited on onlyto the edge seal portions 520-1, 520-2, 520-3 and 520-4.

In exemplary embodiments, the escape paths 450 are formed by selectivelyexposing less than the entire wafer frontside surface area to UVradiation. In alternative embodiments, only portions of the adhesive areUV curable, so that the entire frontside surface of the wafer may beexposed to UV radiation during the pre-cure operation 210 (as for thefully encapsulated tape embodiment illustrated in FIGS. 3A-3C) to form apre-determined pattern of gas escape paths. For example, gas escapepaths 450 may be formed where UV-curable adhesive is utilized while UVinsensitive adhesive is present in regions 420-1, 420-2, 420-3, and420-4).

For the exemplary embodiments, the UV pre-cure is made selective toportions of the frontside area of the thin wafer 301 either by shadowingportions of the adhesive from the UV radiation with a wafer-basedstencil or by scanning the thin wafer 301 under a UV source having spotsize smaller than a diameter of the wafer, along a predetermined paththat passes through the edge seal at one or more locations. In the firstcase, the wafer-based stencil may be affixed to the base film 320 beforeor after wafer thinning to block UV light in the edge seal portions420-1, 420-2, 420-3, and 420-4. Similar to the embodiment where onlyportions of the frontside tape adhesive are UV curable, portions of thebase film 320 may be made to prevent or substantially reduce UVtransmission in the regions disposed over the edge seal portions 420-1,420-2, 420-3, and 420-4 relative to the regions disposed over the escapepaths 450.

A UV source utilized during the pre-cure operation 210 may also beconfigured to have a spot size smaller than a diameter of the thinwafer, for example through use of a stencil or shutter affixed a UVexposure apparatus between a UV source and a chamber where the wafer ispass during pre-cure, or through physically small UV sources, such as,but not limited to, commercially available LED UV sources, disposed inclose proximity to the thin wafer. With a spot size less than thediameter of the thin wafer, the pre-cure operation 210 further entailsdirecting the UV irradiation along a predetermined path that passesthrough the edge seal at one or more locations.

Returning to FIG. 1, at operation 120 the vacuum processing is thenperformed. In embodiments where such processing is at elevatedtemperatures, the wafer and pre-cured frontside tape cooled to below 90°C. As further shown in FIG. 2, vacuum processing operation 120 entails aBSM deposition 120A with the wafer and pre-cured frontside tape cooledby the BSM deposition system. For example, the pre-cured tape may bedisposed on an electrostatic chuck (i.e., base film 320 facing the ESC)and cooled to below 90° C. (e.g., 5-15° C.). A voltage may be applied tothe chuck to electrostatically clamp the thin wafer 301 to the chuckwhile the BSM is sputtered onto the wafer backside while maintaining theadhesive at a temperature below 90° C. While the composition of the BSMmetal or stack of metals may be any known in the art, in the exemplaryembodiment the BSM deposited at operation 120A includes a metal which isdeposited at sufficient power that without wafer cooling, the adhesivewould reach temperatures of at least 175° C. For example, in oneembodiment, BSM deposition entails depositing a thickness of nickelvanadium (NiV) that induces wafer temperatures over 175° C.

Following vacuum processing (e.g., BSM deposition), the frontside tapeis removed at the detape operation 130. Typically at operation 120, thethin wafer is mounted to dicing tape applied to the wafer backside. Inembodiments, the detape operation 130 further entails curing anyun-cured portions of the frontside tape to separate the adhesive fromthe entire wafer frontside surface area. For example, in FIG. 5C edgeseal portions 520-1, 520-2, 520-3, and 520-4 may be cured using standardtechniques for the NRT class of BG tape. For embodiments, where a fullcure was done at the pre-cure operation (e.g., 210), no further cure isperformed at the detape operation 130. Following the detape operation130, conventional die prep activities may then be performed.

FIGS. 6A and 6B illustrate plan and side view schematics of a UV cureapparatus 600 to perform at least the pre-cure operation 210 of the BSMmethod 200, in accordance with an embodiment.

The UV cure apparatus 600 includes a robotic handler 610 upon which thethin wafer 301, as supported by the top side tape (for example includingthe base film 320 and adhesive 510) is disposed during the pre-cureoperation 210. The robotic handler 610 may be any stage, platen, chuck,etc. utilized in a conventional UV cure apparatus. The UV cure apparatus600 further includes a UV source 630, such as, but not limited to a UVsource emitting over any or all of the UV-A, UV-B, or UV-C wavelengths.The UV source 630 may be any source conventional for curingapplications, such as, but not limited to, a lamp having a hot or coldcathode. For embodiments where the lamp emission results in an exposurelength that is at least the diameter of the thin wafer 301, the UV cureapparatus 600 includes a stencil, or shutter, 640 to reduce the UVilluminated spot size to a dimension, L, along at least one dimension(e.g., the y-dimension in FIGS. 6A and 6B). The reduced spot sizedimension L is significantly less than the diameter of the thin wafer301 for which the robotic handler 610 is configured to support (e.g.,less than 300 mm) In exemplary embodiments, L is on the order of tens ofmillimeters.

The UV cure apparatus 600 further includes a controller 675communicatively coupled to the robotic handler 610, to the UV source630, and potentially to the shutter 640, to selectively irradiate a paththrough an adhesive edge seal at predetermined locations about aperimeter of the tape as the wafer 501 displaced relative the UV source630 by the robotic handler 610. As shown in the FIGS. 6A and 6B, asingle-pass scan of the wafer 501 in the x-dimension may be performedtwice with the robotic handler 610 rotating the wafer 501 approximately90° between the two scans. Therefore, the adhesive edge seal 520 isbifurcated into four edge seal portions 520-1, 520-2, 520-3, and 520-4with the gas escape path 550 disposed there between. Widths of the gasescape paths 550 are therefore on the order of the spot size dimension L(e.g., tens of millimeters) while the four edge seal portions 520-1,520-2, 520-3, and 520-4 have arc lengths along the wafer edge that areone hundred millimeters, or more.

FIGS. 7A and 7B illustrate plan and side view schematics of a UV cureapparatus 700 to perform at least the pre-cure operation 210 of the BSMmethod 200, in accordance with an embodiment. The UV cure apparatus 700includes the robotic handler 610 and the UV source 630 (e.g., laser,lamp, etc.). In the optical path between the UV source 630 and the wafer501 is a beam steering apparatus 780, such as a galvanometer drivenmirror. One or more of the robotic handler 610, UV source 630 and beamsteering apparatus 780 is communicatively coupled to a controller 775programmed to automatically direct UV radiation along a predeterminedpath on the frontside surface of the wafer 501 that irradiates a paththrough an adhesive edge seal at predetermined locations about aperimeter of the tape. In further embodiments, spot size may becontrolled through optical elements 770 conventional to the imagingarts, depending on the desired width of the gas escape paths to bescanned. In the exemplary embodiment, the UV source 630 is to irradiatea spot size having a diameter less than a diameter of the wafer 501 andthe spot is to be displaced relative to the wafer in both an x and ydimension across the frontside surface area. As further illustrated inFIG. 7B, the robotic handler 610 displaces the wafer 501 relative to anilluminated spot 760 along a first dimension (e.g., x-dimension) whilethe beam steering apparatus 780 displaces the illuminated spot 760relative to the wafer 501 along a second dimension (e.g., y-dimension).Of course, alternative embodiments where either one of the robotichandler 610 or beam steering apparatus 780 induces displacement in bothx and y dimensions are also possible.

FIG. 8 is a flow diagram illustrating a frontside tape pre-cure method800, in accordance with an embodiment of the present invention. Thepre-cure method 800 may be performed by a UV cure apparatus, such as,but not limited to the UV cure apparatus 600 or the UV cure apparatus700. Method 800 begins at operation 801 with loading the thinned andtaped wafer (e.g., wafer 501) into the pre-cure apparatus. At operation805, a path is irradiated through an adhesive edge seal at predeterminedlocations about a perimeter of the tape. One or more gas escape pathsare thereby formed through a radial thickness of an adhesive edge sealto place an interior area of the frontside tape in fluid communicationwith the environment external to the adhesive edge seal. The wafer isthen unloaded from the pre-cure apparatus for subsequent vacuumprocessing (e.g., sputter deposition of a BSM).

FIG. 9 is a block diagram of a computer system 900 configured as acontroller (e.g., controller 675 or 775) to cause the UV cure apparatusto perform the frontside tape pre-cure method illustrated in FIG. 8, inaccordance with an embodiment of the present invention. The exemplarycomputer system 900 includes a processor 902, a main memory 904 (e.g.,read-only memory (ROM), flash memory, dynamic random access memory(DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), astatic memory 906 (e.g., flash memory, static random access memory(SRAM), etc.), and a secondary memory 918 (e.g., a data storage device),which communicate with each other via a bus 930.

Processor 902 represents one or more general-purpose processing devicessuch as a microprocessor, central processing unit, or the like.Processor 902 may also be one or more special-purpose processing devicessuch as an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), a digital signal processor (DSP),network processor, or the like. Processor 902 is configured to executethe processing logic 926 for performing the operations and stepsdiscussed herein.

The computer system 900 may further include a network interface device908. The computer system 900 also may include a video display unit 910(e.g., a liquid crystal display (LCD)), an alphanumeric input device 912(e.g., a keyboard), a cursor control device 914 (e.g., a mouse), and asignal generation device 916 (e.g., a speaker). The secondary memory 918may include a machine-accessible storage medium (or more specifically acomputer-readable storage medium) 930 on which is stored one or moresets of instructions (e.g., software 922) embodying any one or more ofthe methodologies or functions described herein. The software 922 mayalso reside, completely or at least partially, within the main memory904 and/or within the processor 902 during execution thereof by thecomputer system 900, the main memory 904 and the processor 902 alsoconstituting machine-readable storage media. The software 922 mayfurther be transmitted or received over a network 920 via the networkinterface device 908.

The machine-accessible storage medium 930 may also be used to storedcontrol commands for one or more of the UV source 930 and robotichandler 610. In an embodiment, machine-accessible storage medium 931 maybe used to configure the processor 902 to expose less than an entirefrontside surface area of a wafer having frontside tape to form gasescape paths. While the machine-accessible storage medium 930 is shownin an exemplary embodiment to be a single medium, the term“machine-readable storage medium” should be taken to include a singlemedium or multiple media (e.g., a centralized or distributed database,and/or associated caches and servers) that store the one or more sets ofinstructions. The term “machine-readable storage medium” shall also betaken to include any medium that is capable of storing or encoding a setof instructions for execution by the machine and that cause the machineto perform any one or more of the methodological embodiments of thepresent invention. The term “machine-readable storage medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, optical and magnetic media, and other similar non-transitoryformats.

It is to be understood that the above description is illustrative, andnot restrictive. For example, while flow diagrams in the figures show aparticular order of operations performed by certain embodiments of theinvention, it should be understood that such order may not be required(e.g., alternative embodiments may perform the operations in a differentorder, combine certain operations, overlap certain operations, etc.).Furthermore, many other embodiments will be apparent to those of skillin the art upon reading and understanding the above description.Although the present invention has been described with reference tospecific exemplary embodiments, it will be recognized that the inventionis not limited to the embodiments described, but can be practiced withmodification and alteration within the spirit and scope of the appendedclaims. The scope of the invention should, therefore, be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A backside vacuum processing method, comprising:forming a gas escape path on a thinned wafer that includes a backsideand a frontside with a tape laminated to the frontside, wherein the tapeincludes a base film and an adhesive, and wherein forming the gas escapepath breaches an edge seal formed by the adhesive to place the waferfrontside internal to the edge seal in fluid communication with anenvironment external to the edge seal; and vacuum processing the waverwith the tape dispose on a chuck of a vacuum processing apparatus. 2.The method of claim 1, wherein the vacuum processing comprisingdepositing a backside metallization (BSM) with the wafer and pre-curedtape cooled by a BSM deposition system.
 3. The method of claim 1,wherein forming the escape path further comprises pre-curing the tapeover at least a portion of the wafer frontside surface area to separatethe adhesive from only a portion the wafer frontside.
 4. The method ofclaim 3, wherein the wafer frontside includes topographic features, andwherein pre-curing the tape over at least a portion of the waferfrontside area further comprises exposing the entire frontside surfacearea to UV radiation to separate the adhesive from the wafer frontsideat the edge seal while maintaining adhesive contact with the topographicfeatures.
 5. The method of claim 3, wherein the pre-curing of the tapecomprises selectively exposing less than the entire wafer frontsidesurface area to UV radiation.
 6. The method of claim 5, whereinselectively exposing less than the entire wafer frontside surface areato UV radiation further comprises at least one of: shadowing portions ofthe adhesive from the UV radiation with a stencil; or scanning the waferunder a UV source having spot size smaller than a diameter of the wafer,along a predetermined path that passes through the edge seal at one ormore locations.
 7. The method of claim 5, wherein the adhesive isdisposed only at a perimeter of the base film, and wherein selectivelyexposing less than the entire wafer frontside surface area to UVradiation further comprises at least one of: shadowing a portion of theedge seal from the UV radiation with a stencil; or scanning the waferunder a UV source along a predetermined path that passes through onlyportions of the edge seal.
 8. The method of claim 7, wherein the UVsource has a radiation spot size smaller than a diameter of the wafer.9. The method of claim 1, wherein the thinned wafer is between 150 μmand 400 μm thick and wherein the base film is EVA at least 300 μm thickor is PET of at least 100 μm thick.
 10. The method of claim 9, whereinthe thinned wafer is between 150 μm and 250 μm thick, wherein the basefilm is EVA between 300 μm and 400 μm thick, or is PET between 150 μmand 200 μm thick.
 11. The method of claim 1, wherein depositing the BSMwith the wafer and pre-cured tape cooled by the BSM deposition systemfurther comprises: disposing the pre-cured tape on an electrostaticchuck; electrostatically clamping the wafer to the chuck; and depositingthe BSM onto the wafer backside while maintaining the adhesive at atemperature below 90° C.
 12. The method of claim 11, wherein depositingthe BSM comprises depositing NiV.
 13. The method of claim 2, furthercomprising: laminating the tape to the wafer frontside; backgrinding thewafer before forming a gas escape path; and removing the tape from thewafer.
 14. The method of claim 13, further comprising: curing un-curedportions the wafer frontside after depositing the BSM to separate theadhesive from the entire wafer frontside surface area;
 15. A backsidemetallization (BSM) process, comprising: laminating a backgrind (BG)tape comprising a base film and an adhesive to a frontside of a wafer;backgrinding the wafer to a thickness between 150 and 250 μm; forming agas escape path between the base film and the wafer frontside surfaceafter the backgrinding, the gas escape path breaching an edge sealformed by the adhesive to place the wafer frontside surface internal tothe edge seal in fluid communication with an environment external to theedge seal; depositing the BSM with the wafer and pre-cured BG tapecooled by a BSM deposition system; and removing the BG tape from thewafer frontside.
 16. The method of claim 15, wherein forming the escapepath further comprises pre-curing the tape over at least a portion ofthe wafer frontside surface area to separate the adhesive from only aportion the wafer frontside.
 17. The method of claim 16, wherein thewafer frontside includes topographic features, and wherein pre-curingthe tape over at least a portion of the wafer frontside area furthercomprises exposing the entire frontside surface area to UV radiation tocompletely remove the edge seal while maintaining adhesive contact withthe topographic features.
 18. The method of claim 16, wherein thepre-curing of the tape comprises selectively exposing less than theentire wafer frontside surface area to UV radiation
 19. A tape curingapparatus comprising: a UV source; a robotic handler to handle a waferwith tape disposed on a frontside of the wafer; and a controller coupledto the robotic handler and to the UV source to irradiate a path throughan adhesive edge seal at predetermined locations about a perimeter ofthe tape.
 20. The tape curing apparatus of claim 19, further comprisinga shutter disposed between the UV source and a region where the handleris to displace the wafer in a first dimension during exposure, theshutter to limit a spot size of the radiation to less than a diameter ofthe wafer along at least a second dimension, perpendicular to the firstdimension.